It is common for certain mechanical power transmission devices to employ gear trains and to require especially high reliability to ensure that the device will operate on demand. For example, certain aircraft actuators and actuator systems employ gear trains and require especially high reliability to ensure the operability of the aircraft during all flight modes. A failure, such as a jam, in the gear train of such aircraft actuators and actuator systems is therefore to be avoided. For gear trains, failures, such as jamming, can occur when debris, such as pieces of a bearing cage or a broken or bent gear tooth, enters a gear mesh between two gears.
One approach to obtaining high reliability is to provide the mechanical power transmission device with a high degree of redundancy via multiple load paths between the input and output of the device. Such an approach provides alternate load paths in the event of a failure, such as a jam, in any one of the multiple load paths. However, there are often locations in such devices, such as at a single output member driven by the multiple load paths, where a jam in one of the multiple load paths may prevent operation of the entire device. Additionally, multiple load paths are not feasible in some mechanical power transmission devices due to other requirements and constraints, such as weight or envelope, on the device. The ability to resist a jam can become even more important in such devices.
Thus, it can be seen there is a need for a new and improved mechanical power transmission device that includes a jam-resistant gear or gear train which will allow for the continued operation of the device when debris enters a mesh of the gear or gear train.
Shock loads caused by rapid accelerations and decelerations are another problem encountered by many mechanical power transmission devices, such as aircraft actuators and actuator systems. Often, the anticipated shock loads, rather than the normal operating loads, determine the component sizing for the device. This can result in components that are oversized for their normal operating loads. Accordingly, there is a continuing need for mechanical power transmission devices that minimize the transmitted shock loads, thereby increasing the shock load tolerance of the device and reducing the size and weight of the device.